Selected Projects

Population and community dynamics in dynamic and disturbed landscapes

Environmental conditions for species communities are changing as a result of human activities, in particular due to climate change and altered human land use. The assessment of these impacts on ecosystems is one of the most challenging tasks of present ecological research. The last decades have shown that many species up to communities and ecosystems are not able to cope with these changes and that different communities are impacted in different ways with either positive or negative consequences. Of particular importance in this context is the so-called Intermediate Disturbance Hypothesis (IDH). It explains species coexistence as a result of catastrophic events (disturbances) which hit stronger competitors more severely and therefore compensate for competitive disadvantages between the species. The IDH predicts that species diversity will be highest at intermediate disturbances provided that there is a trade-off in species biology between the ability to tolerate disturbance and the competitive ability. For neutral communities it has been predicted that diversity will decrease with increasing disturbances. However, due to climate change species niches will shift and additional disturbances may arise. Thus, geographic range shifting and disturbance interactions (multiple stressors) will become increasingly important for species communities. Furthermore, there is increasing acknowledgement that the duration of disturbance (pulsed or press disturbance) is important. Therefore, this project intends to bring insights at a theoretical and applied level into these effects with the aim of supporting the development of management strategies and policy advice in the face of climate change. Cooperation with Alexander Singer, Dept. Ecological Modelling, Justin Travis, University of Aberdeen

Functional resilience of aquatic ecosystems under multiple stressors

Aquatic ecosystems are increasingly confronted with multiple pressures. Among them eutrophication (enrichment of algae) as a consequence of agricultural land use and temperature changes due to climate change can be major threats to healthy aquatic ecosystems. Ecosystem based approaches such as biocontrol of eutrophication seem to be promising for improvement of water quality. In river systems biological control is generally possible by clams grazing on algae. In this project we combine concepts of organismic ecology (consumer-resource interactions) with ecosystem processes (functional resilience) to investigate the impact of abiotic environmental conditions (spatial heterogeneities, multiple stressors, climate shifts) on the biocontrol efficiency of clams in order to determine key factors of its functional resilience. This modelling approach is done in close cooperation with river experiments to the benefit for both disciplines. On the one hand models benefit from the experiments by getting data and knowledge about model structure and parameters, on the other hand experiments benefit from models by getting hypotheses for testing. Thus, integrated approaches combining theory, modelling and experiments can be used to study community dynamics under different environmental conditions in order to assess their functioning and the performance of their ecosystem services.

Cooperation with Ricardo Ruiz, Karin Frank from the Dept. of Ecol. Modelling, Marcus Weitere, from the Dept. of River Ecology, Christoph Jäger from Dept. Aquatic Ecosystem Analysis and Management.

consumer-resource interaction: clams and algae

Selected project: Ecological theory in microbiology

Biodiversity and ecosystem functioning

Within this project, the integration of ecological theory and specific theoretical concepts of ecology into microbiology is a promising approach to the benefit for both disciplines. On the one hand microbial experiments can be designed to validate theoretical concepts and predictions of ecological models. On the other hand, findings of controlled microbial laboratory experiments can be understood and interpreted in terms of ecological theories and concepts. Integrated approaches combining theory, modelling and microbial experiments can be used to study community dynamics under different environmental conditions (spatial heterogeneities, stressors, climate shifts), assessing their functioning and performance of ecosystem services and determining key factors of their functional resilience.

Cooperation with Alexander Singer from the Dept. of Ecol. Modelling; Canan Karakoç, Antonis Chatzinotas from the Dept. of Microbiology, Ingo Fetzer from Stockholm Resilience Centre

Mycelia networks in soil decontamination

To find natural attenuation strategies based on the ecological dynamics of microbial communities it is necessary to combine macroscopic ecological theory with microbial knowledge, computer simulation modelling and experiments. The aim is to find and understand relationships between the spatial structure and dynamics of microbial communities and their resulting ecosystem functioning and services. In this project we focus on the natural attenuation and biodegradation capacity. The subsequent design of biodegradation strategies at large spatial scales, the role of mycelial networks in soil decontamination and the robustness of decontamination under different types of environmental stress are investigated for the sustainable and efficient use of the ecosystem service of natural attenuation. This helps developing biodegradation strategies that are not only technology but also ecosystem based.

Cooperation with Thomas Banitz from the Dept. Ecol. Modelling, Lukas Wick from the Dept. of Microbiology

Nutrient fluxes in a plant-fungi interaction

The interplay between nutrient fluxes and nutrient exchange in plant-fungi interactions is studied in a combined model-experiment approach. An individual-based ecological model simulates the growth of arbuscular mycorrhizal fungi exchanging nutrients with a plant. These dynamics are compared with laboratory experiments of mycorrhizal fungi growth to parameterise the processes in the model. Using the model, the consequences of different inter-specific interaction strategies for the carbon and phosphorus flows between fungus and plant are investigated. How much phosphorus the fungus has to deliver for a certain amount of carbon from the plant determines the type of interspecific interaction.

Cooperation with Joachim Kleinmann from the Dept. Ecol. Modelling; Thomas Fester, Frank Zielinski from the Dept. of Microbiology

This project is performed in interdisciplicary cooperation with Martin Drechsler (Department of Ecological Modelling), Frank Wätzold (University of Cottbus), Melanie Mewes (Department of Economy) and Astrid Sturm (Freie Universität Berlin).

Agri-environment schemes in which farmers receive payments for conservation measures are one of the most important policy instruments for conservation in Europe. More than 1 billion € is spent on such programmes each year and the key question is how to design payments in a way that they are cost-effective, i.e. that for available financial resources the conservation success is maximised. The answer to this question is not trivial because the costs and benefits of individual conservation measures differ in space and over time. As conservation budgets are limited only some measures can be selected in a region and the challenge is to design payments in a way that for an available budget they are able to generate the combination of conservation measures which achieves the highest level of conservation. A relatively novel approach to this challenge is ecological-economic modelling which integrates knowledge form ecology and economics. We developed an ecological-economic modelling procedure that is able to quantitatively determine cost-effective payments for measures to conserve endangered species when cost and benefits of measures differ in space and depend on the timing of land use. The procedure integrates an agro-economic model, an ecological simulation model and a numerical optimisation module. The agro-economic model calculates the costs of single grassland measures or of a certain pattern of measures in a region. The ecological simulation model calculates the ecological effect on species in dependence on the location and timing of the measures. The numerical optimisation module integrates the ecological and economic model and calculates the cost-effective land use pattern for a given financial budget including the corresponding compensation payments which have to be paid to achieve this pattern. Presently, we are developing a decision support software called DSS-Ecopay which can be used for evaluating agri-environment schemes.

Selected project: Geographic range shifting of species and communities in dynamic landscapes

The region of suitable habitat (green) is described as a climate window which shifts across the landscape during climate change. Individuals or populations in unsuitable patches (black) go extinct.

Spatial distribution of a butterfly (red) and its host plant (green).

There is an increasing acknowledgement that we are experiencing a period of climate change. Therefore, it is important to understand whether and how species and communities are able to cope with shifts in their environmental conditions or with increasing fragmentation. Predictions of specific species future geographical range are often considered through climate niche models. These models are essentially statistical, and pay little attention to species life-history traits (e.g. dispersal) and the type of intraspecific and interspecific competition. Both processes can influence geographic range shifting and thus the ability of species and communities to cope with climate change. However it is still unclear how the biotic versus the abiotic environmental conditions influence geographic range shifting due to climate chnage. Especially interesting and challenging is the question how communities of species respond to climate change and how dynamics and biodiversity change. This requires understanding of the basic mechanisms of species coexistence.Furthermore, alterations of species traits and competitiveness through mutations can influence the spatial distribution and persistence of species and communities under climate change. Therefore the combination of ecological and evolutionary dynamics might be essential in predicting the consequences of climate change for ecosystem dynamics, functioning and diversity.